Magneto drive



E. A. JOHNSTON.

' MAGNET!) DRIVE.

APPLICATION FILED SEPT. 9 1916.

Patented Mar. 7, 1922.

2 SHEETS-SHEET I.

E. A. JOHNSTON. MAGNETO DRIVE.

APPLICATION man SEPT. 9, 1916.

PatentedMar. 7, 1922 2 suans-sussf 2.

llllli Inva UNl'llilll STATES PATEN' UFFICE.

EDNARD A. JOI'INSTGN, OF CHICAGO. ILLENOIS, ASSIGNOE, BY LIESNE ASSIGNMENTS, TO INTERNATIONAL HARJ'ESTER COBZPANY, A CORPUEELTIGN OE NEW J'ERSEY.

BEAGNE'IO DRIVE.

Specification of Letters Patent.

Patented Mar. 7, 1922.

Application filed September 9, 1916. Serial No. 119,166.

To all whom it may concern:

lie it known that l, EDWARD A. Jonnsron, a citizen of the Umted States, residing at Chicago, in the county of Cook and State of Illinois, have invented certain new and useful Improvements in Magneto Drives, of which the following is a full, clear, and exact specification.

This invention relates to magneto drives.

One of the objects of my present invention is to facilitate and simplify the start ing ans operation of magnetos to generate a current to produce sparks of sufficient volume ignition purposes during the starting movements of an internal combustion engine, as well as during normal running.

Another object of my invention is to improve the drive of magnetos for starting and running purposes.

Another object of the invention is to provide a magneto starter adapted to meet all the requirements for successful commercial operation.

These and other objects are accomplished by providing a magneto with a starter which transmits to the armature of the magneto a speed which is greater than that of the driving shaft under starting conditions, and. which automatically changes this speed to the driving shaft speed when a certain predetermined speed has been reached.

The invention is illustrated on the accompanying sheets of drawings, in which- Figure 1 is a fragmentary end elevation of the cylinder of an internal combustion engine equipped with a magneto and starter embodying my invention Figure 2 is a side elevation of the same;

Figure 3 is a cross sectional view showing the general arrangement of the gears which transmit motion from the cam shaft gear to the magneto armature;

Figure 4 is a fragmentary end elevation of a magneto, parts being in section, showing the planetary gear arrangement; and

Figure 5 is a detail sectional view reduced in size, showing the notches on the inner surface of the driving gear cooperating with a pawl on the carrier to insure proper timing of the spark.

The various novel features of my inven tion will be apparent from the following description and drawings, and will be particularly pointed out in the appended claims.

To provide a simple, compact and efficient magneto starter to meet the-various require ments for successful commercial operation has been a problem which has confronted engineers for some little time. This is especially true wl ere a magneto is required to produce sparks during the starting of an internal combustion engine. As is well known, a very common practice is to start the engine on battery current and then switch over to magneto current when the engine speed has increased sufiiciently to drive the magneto at a speed high enough to obtain a spark suflicient volume to insure efficient ignition of the explosive charge. The magneto being driven by the engine to which it is furnishing the spark, it is evident that the speed of the magneto is a function of the speed of the engine. If the magneto were geared to a gas engine in a given manner to produce a spark of suflicient volume during the starting of the gas engine, the speed of the magneto during normal operation o the engine, assumingthat the same gearing relationship exists, would be excessive. On the other hand, if a magneto were geared to a gas engine in a relation for proper running conditions, this magneto with the game gearing relation would not be driven at a speed high enough to insure a spark of sufllcient volume for ignition purposes during the starting of the engine. I have overcome this problem by providing a driving connection between the internal combustion engine and magneto armature such that the speed of the magneto is sufiiciently high or attains a speed which is a multiple of the cam shaft speed of the engine to produce a spark of sufficient volume for efficient ignition purposes during the 1 starting mo. ement, and which automatically changes its driving relationship when the engine has attained a certain predetermined speed, whereupon the magneto armature is driven at driving shaft speed.

Reference now being had to Figures 1 and 2 f the drawings, it will be seen that the cylinc or 10 of the internal combustion enis shown as having a cylinder head 11,

the movable electrode having secured thereto an eye member 1 1, through which passes a trip rod 15. The end of the trip rod lies in the path of movement of a cam 16 on the cam shaft 17 of the internal combustion engine, the cam 16 pushing the trip rod 15 to the left, as shown in Figure 1, against the tension of a spring 18 surrounding the rod 15, one end of which spring is suitably anchored to a stationary member 19, the other end of which is secured to an adjustable collar 20 mounted on and secured to the rod 15. As is well understood, when the cam 16 has passed beyond the rod 15 after pushing it to an extreme limit of movement, the stretched spring 18. draws the rod 15 in a reverse direction with a snap action, whereby a hammer blow is dealt to the eye member 14 by the head 21 of the rod to instantaneously separate the stationary and movable electrodes, whereupon, a spark is produced for igniting an explosive charge within the combustion chamber.

The bracket 22 which supports the shaft 17 has a horizontally arranged portion 23 which supports the magneto 24. Mounted upon one end of the (am shaft 17 is a gear which meshes with and drives a gear 26, which hereafter I will call the driving gear. This driving gear 26 is ro tatably nounted upon a sleeve 27 which is keyed to the shaft 28 of the magneto armature, represented by the portion 29. Secured to the driving gear 26 by suitable pins 30 is a concentrically arranged gear 31 which meshes with oppositely arranged smaller gears 32 and 33 forn'iing a part of a planetary gear arrangement including larger gears 34: and 35, which are secured to or formed integrally, respectively, with the gears 32 and 33. The planetary gears 82 and 3.4 are rotatably mounted upon a stud and planetary gears and 35 are rotatably mounted upon another stud 37, both of which studs are secured to a carrier 38 loosely mounted on the armature shaft 28. Secured to or formed integrally with the sleeve 27 is a gear 9 which meshes with the planetary gears 34: and The various parts mounted on the armature shaft 28 are retained thereon against lateral movement by a suitable nut 39 engaging a threaded end portion of the armature shaft 28. The gearing just described transmits rotary movement from the engine cam shaft- 17 to the magneto armature 29.

As above mentioned, when the engine is being started, its speed necessarily is low, and the speed of magneto driven from the engine is too low when hooked up to the engine for normal running purposes to produce a spark of sufficientvolume. lt is apparent, therefore, that if the sparks to be used for starting internal combustion engine are caused by current generated by the magneto, the magneto must be driven at a speed which is in excess of the cam shaft speed of the engine. 1 have found by experiment that if the magneto armature is driven at a speed three times that of the engine cam shaft speed under starting conditions, proper ignition of the explosive mixtures should be effected. A three to one speed with the size and arrangement of gears shown in Figures 3 and 4, is obtainable when the carrier 38 of the planetary gears is held in a stationary position. This is accomplished by providing a member 40 having a stop portion 41 which, under certain conditions, lies in. the path of movement of a projection 42 extendinglaterally from and secured to one side of the carrier 38. With the driving gear 26 rotating in a clockwise direction, as indicated by arrows in Figures 1 and i, the carrier 38 also will tend to move in the same direction. However, with the stop portion ll of the member 4-0 lying in the path of movement of the projection 1-2, the carrier will be arrested against movement. The member 40 held in a position to retain the carrier 38 against movement by a properly supported spring 43, one end of which engages a notch 4.4- in the member 40; that is to say, the stop member is yieldingly locked in a position to prevent rotative movement of the carrier 38 in a clockwise direction under starting conditions. However, when the speed of the engine has increased a predetermined amount; that is, when the cam shaft speed is sufficiently high for driving the magneto armature at the same speed to produce a spark capable of igniting an explosive charge, the member 40 with its stop portion 4-1 will be automatically thrown out of the path of movement of the projection 42 whereupon the carrier is free to rotate. To automatically release the carrier 38, therefore. .l have provided a speed governing device including a weighted member 45 which is pivotally connected to a member 4:6 secured to the inner side of a flanged portion 47 of the driving gear This weighted member 45 is responsive to centrifugal ac tion, and when the gear member 26 has attained a certain predetermined speed, a projection 4.8 secured to the weighted member {15 projects out through an opening 49 and c1 a -es a cam portion 501 of the member 40 which pivotally mounted on a stud 51. automatically swinging the member 40 with its cam portion 50 and stop portion 41 to the right, as viewed in Figure in a manner to free the carrier so that the latter may rotate. lVhen the member -10 is thrown from its stopping position, shown in Figure 2, the notch it is snap ed beyond the end of the spring 13, which then falls into another notch in the member 10, thereby yieldingly locking the member 40 in an inoperative position; that is to say, such that the stop portion 41 is out. of the path of movement of the projection 42 on the carrier 38.

As stated above, when the carrier is held againstmovement, the speed of the magneto armature 29 is three times as great as the speed of the cam shaft. However, when the carrier is automatically released, the speed of the cam shaft and magneto armature is the same, the driving gear 26 and carrier 38 being locked together under such normal operating conditions. This locking action between the driving gear 26 and carrier 38 under normal operating conditions is caused by the action or resistance of the armature against rotation, caused primarily by the flux between the field poles of the armature. It is important that the carrier 38 should not rotate faster than the driving gear 26 under normal operating conditions. F or this reason I have provided the carrier (see Figure 5) with a pawl or dog 53 which is adapted to engage either of two notches 54 formed on the inner side of the driving gear 26. These notches 5e are properly spaced to insure a proper timing action. If it were not for the cooperative action between these notches 54: and pawl 53, the carrier would be free to revolve faster than the gear 26, in which event there would be no rotation of the magneto armature, the result being no spark. Again, if the armature rotated but a little; that is to say, if there was a slipping action between the carrier 38 and driving gear 26, the breaking or the separation of the igniter points would occur at a time when the output of the magneto would be insufficient to cause a spark, or, at least, one of suflicient magnitude.

By means of my magneto drive, therefore, the magneto armature may be driven at a speed which is a multiple of the engine cam shaft speed for starting purposes and automatically changed to cam shaft speed when the cam shaft speed has attained a certain predetermined magnitude to insure the production of sparks of proper volume to meet requirements for efficient ignition purposes.

There may be various modifications of my invention other than here shown and nescribed, and it is my intention to cover all such modifications which do not involve a departure from the spirit and scope of my invention as set forth in the following claims.

What I claim as new is:

1. In combination, a drive shaft, a driving member rotatable thereon and formed with a lateral flange, a variable speed transmission device on the shaft and connecting it with the driving member, and means mounted on the flange and controlled by centrifugal force for altering the operation of the transmission device to change the drive speed.

2. In combination, a drive shaft, a driving member rotatable thereon and formed with a lateral fiange, a variable speed transmission device on the shaft and connecting it with the shaft including a rotatable element having a lock, and means mounted on said flange and controlled by centrifugal force for disconnecting the lock from the rotatable element at predetermined speed of the driving element.

3. In a drive for a magneto, a driving member, a carrier, gears mounted on said carrier operatively connected to said driving member, means whereby said carrier may be held against movement, and means for automatically releasing said carrier.

4. In a drive for a. magneto, a driving member, a carrier, gears mounted on said carrier operatively connected to said driving member, means whereby said carrier may be held against movement, and means responsive to changes in speed for releasing said carrier.

5. In a drive for a magneto, a driving member, a carrier, gears mounted on said carrier operatively connected to said driving member, means whereby said carrier may be held against movement, and means responsive to centrifugal force for releasing said carrier.

6. In a drive for magnetos, a driving member, a carrier, gears supported by said carrier and operatively connected to said driving gear, a stop member for arresting movement of said carrier, and speed governing means mounted on said driving member for actuating said stop member to release said carrier.

7. In combination, a. magneto having an armature, a driving member, a carrier, gears supported by the carrier operatively con necting said armature and driving member, a member for holding the carrier against movement whereby one speed may be trans-- mitted to the armature, and means rotatable with the driving member and controlled by its speed for releasing the carrier for transmitting a different speed to the armature.

8. In a drive for magnetos, a magneto shaft, a driving shaft, means connecting the two shafts including a rotatable member, gears rotatably mounted thereon for driving the magneto shaft at one gear ratio at starting and at another fixed gear ratio after a certain speed has been attained, and means carried by the rotatable member and controlled by its speed for shifting from one gear ratio to the other.

9. In drive for magnetos, a magneto shaft, a driving shaft, means connecting the two shafts including a rotatable member, gears rotatably mounted thereon for driving the magneto shaft at one gear ratio at starting and at another fixed gear ratio after a certain speed has been attained, and means for'automatic-ally shifting from one gear ratio to the other.

10. In a drive for magnetos, a magneto shalt, a driving shaft, means connecting the two shafts including a rotatable member, gears rotatably mounted thereon for driving the magneto shaft at one gear ratio at starting and at another fixed gear ratio after a certain speed has been attained and gov- 10 ernor controlled means for shifting from one gear ratio to the other.

In testimony whereoi I aflix mysignatnre.

EDWARD A. JOHNS ION. 

